At the end of the first season of Stranger Things – after Eleven disintegrates the Upside Down monster in the High School and everything feels like a happily ever after – we see Will cough up an otherworldly slug in his bathroom.

One monster might have been defeated, but the Upside Down lingers. And that's how its creators the Duffer Brothers set Stranger Things up for its second season, which premieres on Netflix on October 27.

While we know a few new details, vague plot outlines and character descriptions, we don't know much about where Stranger Things specifically is heading in its second season. We especially don't know what type of evil the people of Hawkins, Indiana, are going to be facing this time.

If you look closely in the poster, you might see something inside those evil clouds. Fans have combined that image with the tagline in the teaser to come up with some interesting theories about the next season.

Is it just me or does the new monster not look like an actual physical creature? It looks like it's made of cloud. I'm guessing that the monster is actually in the Upside Down, but somehow the barriers between the different dimensions are breaking down and, just like the trailer said, "the world is turning upside down".

Pretty much. Maybe the monster has a physical presence in both dimensions. In our world it creates these storms and takes on this cloud-based appearance, and then in later episodes the characters go into the Upside Down and see the real creature in all it's glory. Or maybe it fully enters our world, becoming a real physical creature. Not exactly sure how a group of kids will take down a monster that huge though. Maybe they'll get the military involved.

Regardless, things aren't looking good for the Hawkins crew. Hopefully they can entice Eleven with some Eggos to come back and fight the damn thing.